According to a new review I co-authored in Tobacco Control, heated tobacco products are usually sold by tobacco companies that are not as sold as cigarettes, but can pose health risks to users. There is limited evidence of health risks among smokers, sometimes contradictory and difficult to understand.

Heated tobacco products are electronic devices for hot tobacco, so users can inhale nicotine. Common brands include IQOs available in the United States, as well as Ploom and Glo for sale in other countries.

Heated tobacco products are different from e-cigarettes, although they may look similar. Also known as VAPE, e-cigarettes heat liquids containing nicotine but tobacco, while heated tobacco products heat actual tobacco leaves. Heated tobacco products are also different from traditional cigarettes, which burn tobacco instead of heating. These differences are important because it is the burning of tobacco leaves (rather than nicotine) that directly cause the diseases and deaths associated with smoking.

Long-term data on the health hazards of heating tobacco products are limited. My colleagues and I analyzed available data from 40 clinical trials that followed participants who used these products for one year or less. We studied molecular changes in blood, breathing, and urine, called biomarkers, to explore the potential risks of heating tobacco products.

The study we reviewed reported changes in 143 different biomarkers, including measures related to heart disease and cancer. However, it is very difficult to draw clear conclusions from the data due to the problem of available evidence. Of the 40 studies, 29 were funded by the tobacco industry. Furthermore, 31 of the 40 studies were conducted in a narrow environment, meaning that participants’ activities and their use of the dispensed products were controlled. This may not reflect the realistic use of heated tobacco products.

If heated tobacco products are less harmful than cigarettes, we hope to see beneficial effects among smokers who turn to them. However, the evidence we review is inconclusive. Although most studies have shown that heating tobacco products may reduce the risk of disease compared to smoking, other studies have found no difference, or even the potential to increase the risk. Using heated tobacco products has a more consistent harmful effect than quitting smoking completely.

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Few studies have directly compared the effects of heating tobacco products with e-cigarettes. However, many independently funded long-term studies have examined e-cigarettes and show that they can help people stop smoking and reduce health risks for those who have completely switched from smoking to smoking.

Why it matters

Heated tobacco products may come to a town near you, or are already there. They are already widely used in Japan. iqos was withdrawn from the U.S. market in 2021 after a court ruled that the product infringed existing patents. However, after a series of promotions, IQO was relaunched in Austin, Texas in March 2025. Like most brands of caloric tobacco products, IQOS is owned by Philip Morris International, one of the world's largest cigarette companies.

The company claims it wants to bring IQO to the U.S. market to provide a "better option" for cigarettes for smoking adults. However, we have reviewed the science of whether heating tobacco products is healthier. Our review found inconsistent data on health effects, and other studies suggest that these products may not help smokers quit smoking.

Don't know yet

We don’t know the long-term health effects of heating tobacco products, nor do we know whether they can really reduce the risk of disease and death in people who switch from smoking to using heating tobacco products. It is unclear how heated tobacco products can fit into the wider tobacco and nicotine market, especially given other available products and interventions that have been proven to help smokers quit.

Although our findings do not rule out the possibility that these products have less health risks than cigarettes, they have little support for such claims.